JP3403128B2 - Method and apparatus for manufacturing resin tip body for ballpoint pen - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a resin chip body for a ballpoint pen.

[0002]

2. Description of the Related Art Conventionally, metal is used for the tip body of a ballpoint pen. Manufacturing a chip body using a metal such as stainless steel requires more than 20 high-precision processing steps, the machine therefor is expensive, and the operation requires skill. Therefore, it has been proposed to construct the tip body of the ballpoint pen using a synthetic resin that is easy to process, and some have been put into practical use, but the writing performance and durability are not as good as those of the metal tip ballpoint pen.

The tip is an important part that determines the performance of the ballpoint pen, and the size and shape of the ball receiving seat at the tip of the tip body, the specularity of the receiving surface, the ink guiding groove,
Strict standards are required for processing accuracy and hardness of ink guide holes. Since the chip body to be molded is a minute component and the above-mentioned parts are extremely minute, the mold for molding and the cores necessarily have a minute size. Therefore, in a general synthetic resin molding method, the cores are immediately damaged by the injection flow-in pressure of the molten resin, and mass production of high-quality molded products cannot be expected. Also,
One of the major problems of the synthetic resin chip is that the ball receiving seat lacks in hardness and specularity. Due to the lack of these, the smoothness and durability of the rotation of the ball are lacking.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to manufacture a resin tip body for a ballpoint pen having a high precision, a ball receiving surface having a high hardness, and an excellent mirror surface property, by a simple method and device. It is a thing.

[0005]

SUMMARY OF THE INVENTION According to the present invention, in the production of a resin tip body for a ballpoint pen, the ball receiving seat peripheral surface of the resin tip body is provided immediately after the molten resin is filled in the cavity for molding the tip body. It is characterized by locally applying pressure. That is, a moving core having a pin projection for forming an ink guide hole and a receiving seat forming portion for forming a ball receiving seat is made to face the opening end of the chip body forming cavity and melted in the cavity. Immediately after filling the resin, the moving core is moved to the base side of the cavity, and the ball seating peripheral surface of the resin chip body is locally pressed by the seating molding part. . The inventions of claims 2 to 4 relate to an apparatus used for carrying out the invention of the above method.
That is, the resin chip body manufacturing apparatus is constituted by the cavity for molding the chip body and the moving core disposed on the tip side thereof. The moving core has a pin projection for forming an ink guide hole and a receiving seat forming section for forming a ball receiving seat. The seat forming portion has a peripheral surface shape corresponding to the ball receiver of the chip body, and is configured to reciprocate between the open end of the cavity and the inside of the cavity. It is preferable that a plurality of ridges for forming the ink guide groove be formed in the axial direction on the peripheral wall of the pin projection of the moving core (claim 3) . The tip side of the pin projection of the moving core is mounted in the cavity. It is preferable that the fixed core is fitted into the receiving hole (claim 4) .

[0006]

In the method of the present invention, immediately after the molten resin is filled into the cavity for molding the chip body, the ball receiving seat peripheral surface of the resin chip body is locally localized at the receiving seat molding part of the moving core. When pressure is applied, the resin in the ball receiving seat portion is compressed by the pressure, so that the resin density is improved and the hardness is increased. Moreover, the surface of the ball seat is mirror-finished by this pressurization and compression. Therefore, it is possible to obtain a chip body excellent in hardness and specularity, that is, a resin chip body excellent in durability and smoothness of rotation. Also,
The local pressurization also improves the transferability of the metal cavity. According to the second aspect of the present invention , the ink guide hole is formed by the pin projection for forming the ink guide hole provided on the moving core. Then, when the moving core is moved to the inside of the cavity by a predetermined distance immediately after filling the cavity with the molten resin, the receiving seat molding portion locally pressurizes the ball receiving seat portion of the resin chip body during molding. . In the invention of claim 3, since the ridge for forming the ink guide groove is provided on the peripheral wall of the pin projection of the moving core, a plurality of ink guide grooves are formed in one molding step. . Further, according to the invention of claim 4, since the tip of the pin protrusion of the moving core is held by the fixed core mounted in the cavity, the pin does not easily fall down when the resin is filled, and the ink guide hole is formed. The accuracy of is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a mold 1 is provided with a cavity 2 for molding a resin chip body, and an opening 3 is formed at the narrowed tip of the cavity 2. The main core pin 4 is arranged on the central axis of the cavity 2. The main core pin 4 is located at the position shown in the figure when the molten resin is filled in the cavity 2, and is configured to retreat to the right side in the figure at the time of mold release, and the pin projection of the moving core described later along the central axis A receiving hole 5 for fitting is provided.

A holder 6 for a moving core is attached to the tip surface of the mold 1. The holder 6 has the mold 1
A through hole 7 is provided at a position corresponding to the opening 3 of the moving core 8 and a moving core 8 is slidably mounted in the through hole 7. The moving core 8 is made of a resin chip body 9 (see FIG. 3).
Of the ball receiving seat 10 having a cylindrical shape having an outer shape corresponding to the inner diameter of the ball receiving seat 10. The pin projection 13 has a diameter, and the outer diameter of the pin projection 13 corresponds to the inner diameter of the ink guide hole 14 of the resin chip 9. The tip end side of the pin protrusion 13 is fitted in the receiving hole 5 of the main core pin 4. On the peripheral surface of the pin projection 13 of the moving core 8, a plurality of (four in the figure) convex lines 15 for forming ink guiding grooves are formed at equal intervals and parallel to the central axis.

In the above description, the moving core 8 reciprocates by a hydraulic cylinder (not shown), but is operated by a drive source of a system different from the drive source for opening and closing the mold. That is, when the mold clamping is completed, the main core pin 4 waits at the most advanced position shown in the figure, but at this time, the base 11 of the moving core 8 is located outside the cavity 2 and the receiving seat forming part 12 is formed.
Only the pin protrusion 13 is located in the cavity 2 (position A in FIG. 1). Immediately after the molten resin is filled, that is, after the filling and before the resin is cured (for example, 0.01
It is controlled so as to move in the cavity direction by a predetermined dimension (for example, 0.3 mm) (see position B in FIG. 1) from the second to the 0.10 second.

Hereinafter, the operation of the apparatus of the above embodiment and the embodiment of the invention of the method will be described. When the mold clamping is completed, the main core pin 4 is at the most advanced position and the moving core 8 is at the retracted position (A in FIG. 1) as described above. In this state, the molten resin 18 is injected and filled in the cavity, and immediately after the filling is completed, the moving core 8 is advanced to the position B in FIG.
A ball receiving seat 10 is formed in the resin chip body 9 by the movement of the moving core 8. In addition, since the volume of the cavity 2 is reduced by the volume of the moving core 8 that has entered the cavity due to the movement of the moving core 8 (reference numeral V in FIG. 2), the resin in the ball receiving seat portion is locally compressed. , High density. Therefore, a ball receiving seat with high hardness and high mirror surface can be obtained.

In the above-described embodiment, since the ridge 15 for forming the ink guide groove is provided on the peripheral surface of the pin protrusion 13, the ink guide groove 16 can be formed at the same time when the resin is filled, and the ink guide groove is formed. Since the resin is also compressed in the 16th portion, a highly accurate ink guide groove can be obtained. Further, in the above-described embodiment, since the tip end side of the pin protrusion 13 of the moving core 8 is fitted in the receiving hole 5 of the main core pin 4, the pin protrusion 13 is supported at both ends, so that the pin pressure caused by injection pressure It is possible to obtain a highly accurate ink guide hole without causing a fall. By the way, the pin protrusion 13
In the case of cantilever support, there is a possibility that the pin may fall down during injection, the thickness of the tip of the resin chip may be uneven, and the life of the pin may be shortened.

A metal ball is attached to the resin chip body manufactured by the method and apparatus of the present invention to obtain a ballpoint pen chip. Although the ball mounting method does not limit the present invention, for example, the following method,
A device can be employed.

That is, the metal balls 17 expanded by heating
Is put into the ball receiving seat 10 of the resin chip body 9, and is pressed against the outer surface of the metal ball 17 while softening the outer peripheral surface tip side edge portion of the receiving seat 10 of the resin chip body 9 with a heating tool.
Then, when the metal ball 17 and the resin chip body 9 are cooled, the expanded metal ball 17 contracts, and an appropriate gap 29 (FIG. 10) is obtained between the receiving seat 10 and the metal ball. Since the appropriate gap between the receiving seat and the ball differs depending on the type of ink, the degree of thermal expansion should be set appropriately in consideration of the expansion rate of the metal ball.

FIG. 4 shows an apparatus for mounting metal balls. On the turntable 21, the resin chip supply stage 2
2, metal ball loading stage 23, caulking stage 2
4, 4 sets of take-out stages 25 are faced. A large number of set pins 26, on which resin chips are fitted, are erected on the turntable 21 at equal intervals, and a metal ball rotation break-in metal plate 27 is provided above the turntable between the caulking stage 24 and the take-out stage 25. Is installed parallel to the turntable surface.

In the resin chip supply stage 22, the resin chip body 9 is supplied to the turntable side from the vibrator parts feeder 22a installed above the turntable 21 with the receiving seat 10 thereof facing upward, and fitted into the set pin 26. It is mounted (see FIG. 5).

The metal ball loading stage 23 is heated and expanded from the cartridge 23a having a heating means installed above the turntable 21 and heated and expanded.
Is inserted into the receiving seat 10 of the resin chip body 9 fitted to the set pin 26 (see FIG. 6).

The caulking stage 24 has a caulking tool 24a installed above the turntable 21 so as to be vertically movable. The caulking tool 24a has its tip heated by electromagnetic induction or other heating means 24b.
When the caulking tool 24a descends while rotating, the tip portion of the resin chip body 9 is softened and pressed against the peripheral surface of the metal ball 17, so that caulking is performed quickly without distortion due to excessive external pressure (FIG. 7). reference). Then, when the caulking tool 24a rises, the metal ball 17 is cooled and contracts, and the tip portion of the chip body is hardened, so that the metal ball 17 and the ball receiving seat are properly spaced. Is installed.

The metal ball rotation conditioned metal plate 27 is
It is installed above the turntable 21 between the caulking stage 24 and the take-out stage 25, and the metal ball 17 mounted on the resin chip mounted on the set pin 26 comes into contact with a predetermined pressure, and the rotation state thereof is It can be inspected (see FIG. 8).

The take-out stage 25 is provided with a removing device 25a for removing the resin chip 9 from the set pin 26. In the removing device shown in FIG. 9, pressurized air is supplied to the through holes provided above and below the set pin 26 to lift the resin chip 9 and remove it from the set pin, and the air hole 25b is removed from the set pin. It has an air hole 25c for ejecting the resin chip to the outside of the turntable.

In the apparatus configured as described above , the turntable 21 is rotated while being stopped at each stage, and a predetermined process is performed at each stage, so that the resin chip 28 having metal balls mounted thereon (see FIG. 10). ) Is obtained.

[0021]

According to the present invention, in molding the resin chip body, the ball receiving seat portion is locally pressed, so that the resin density of the ball receiving seat portion is improved and high hardness can be obtained. High specularity can be obtained. Further, the mold transfer property is also improved by applying pressure after filling the molten resin. Therefore, in addition to solving the problem of durability which has been caused by insufficient hardness in the conventional resin chip, the problem of smoothness of rotation of the ball which has been caused by insufficient specularity is also solved. Also, the claims
According to the third invention, it is possible to simultaneously molded with precise ink guide grooves even chip body machining is required, the processing step is further reduced, the ink induction hole shaped according to the invention of claim 4 Since the pin protrusions are supported on both sides, there is an effect that the processing accuracy is improved without causing the pins to fall due to the injection pressure at the time of filling, and the life of the pins is extended.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view showing compression of the ball receiving seat.

FIG. 3 is a cross-sectional view showing a state in which balls are fitted to the resin chip body manufactured according to the present invention.

FIG. 4 is a plan view of the ball mounting device.

FIG. 5 is a front view of a chip supply stage of the ball mounting device.

FIG. 6 is a front view of a ball supply stage of the ball mounting device.

FIG. 7 is a sectional view of a caulking stage of the ball mounting device.

FIG. 8 is a front view of a smoothed metal plate of the ball mounting device.

FIG. 9 is a sectional view of a take-out stage of the ball mounting device.

FIG. 10 is a sectional view of a resin chip on which a ball is mounted.

[Explanation of symbols]

1 mold 2 cavities 3 openings 4 main core pins 5 receiving holes Holder of 6 cores 7 through holes 8 moving core 9 Resin chip body 10 ball catch 11 base 12 Receiving seat forming part 13 pin protrusion 14 Ink guide hole 15 convex stripes 16 ink guide groove 17 metal balls 21 turntable 22 Resin chip supply stage 22a Parts feeder 23 Metal Ball Loading Stage 23a cartridge 24 caulking stage 24a Caulking tool 25 Take-out stage 25a removal device 25b air hole 25c air holes 26 set pins 27 Rotation break-in metal plate 28 resin chips 29 Gap

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B43K 1/08

Claims (4)

(57) [Claims] 1. A moving core having a pin projection for forming an ink guide hole and a receiving seat forming portion for forming a ball receiving seat is made to face an opening end of a cavity for forming a chip body, and the inside of the cavity is formed. Immediately after filling the molten resin into the core, the core is moved to the base side of the cavity, and the peripheral surface of the ball receiving seat of the resin chip main body is pressed by the receiving seat molding part. Chip body manufacturing method 2. A chip main body forming cavity and a moving core arranged at the tip side thereof, the moving core comprising a pin projection for forming an ink guide hole and a receiving core for forming a ball receiving seat. A seat forming part, wherein the receiving seat forming part has a peripheral surface shape corresponding to the ball receiving seat of the chip body , and is configured to reciprocate between the opening end of the cavity and the inside of the cavity. A device for manufacturing resin chip bodies for ballpoint pens 3. The apparatus for manufacturing a resin tip body for a ball-point pen according to claim 2, wherein a ridge for forming an ink guide groove is axially formed on the peripheral wall of the pin protrusion of the moving core. 4. The pin projection of the moving core is fitted in the receiving hole of the fixed core whose tip side is mounted in the cavity.
Or the manufacturing apparatus of the resin chip body for the ballpoint pen according to 3.